Many functions of modern devices in automotive, consumer and industrial applications, such as converting electrical energy and driving an electric motor or an electric machine, rely on semiconductor devices. For example, Insulated Gate Bipolar Transistors (IGBTs), Metal Oxide Semiconductor Field Effect Transistors (MOSFETs) and diodes, to name a few, have been used for various applications including, but not limited to switches in power supplies and power converters.
For example, such a power semiconductor transistor comprises a plurality of MOS control heads, wherein each control head may have at least one trench gate electrode and a source region and a channel region arranged adjacent thereto. For setting the transistor into a conducting state during which a load current in a forward direction may be conducted, the gate electrode may be provided with a control signal having a voltage within a first range so as to induce an inversion channel within the channel region. For setting the transistor into a blocking state during which a forward voltage may be blocked and flow of the load current in the forward direction is avoided, the gate electrode may be provided with the control signal having a voltage within a second range different from the first range so as to induce a depletion region at a pn-junction formed by a transition between the channel region and a drift region of the transistor, wherein the depletion region is also called “space charge region” and may mainly expand into the drift region of the transistor. The channel region in this context frequently is also referred to as a “body region”, in which said inversion channel may be induced by the control signal to set the transistor in the conducting state. Without the inversion channel, the channel region forms a blocking pn-junction with the drift region.
During the time when the control signal provided to the gate electrode has a voltage within the second range, the transistor shall usually not go over to the conducting state. An uncontrolled change of state can result in a malfunction or even a destruction of the transistor.